Persson will be called in for questioning before the police holiday, said Eskilstuna chief prosecutor Lars Lundin.
The case is being handled by the local police in Flen. The investigation was opened after the Swedish Work Environment Authority (SWEA) in Linköping reported the building project – and those legally responsible for it, Persson and his wife Anitra Steen – to the prosecutor in April.
The couple are accused of breaking two rules. The first is that the project is of such a scale that a preliminary report about the construction should have been submitted before the work began.
But what is seen as being more serious is the fact that there was no workplace health and safety plan for the project.
The punishment could be a fine of up to 39,000 kronor for Persson, according to Aftonbladet.
If he admits breaking the law and accepts the punishment, the case need not come to court, Lars Lundin told the paper.
On Saturday morning Göran Persson was was reporting back to parliament on the recent EU summit and did not want to comment on his building difficulties.